Split your fleet and corner them for inland seas. For open seas split off a group of light ships only, since fleet speed is restricted to the slowest ship type, you can chase down enemy fleets consisting of heavies and then catch up later with your own heavies.
I just remembered that the AI also knows when your ships are at low maintenance and it blatantly blockades the port where a much superior force is stationed because of that knowledge; whenever I see that I like to raise the maintenance one day before the end of the month (because the AI instantly knows when I raise it and tries to run) then sail out to kill it. The AI cheats at so much stuff that it would probably be faster to list what the AI does not cheat.